Preliminary Bulletin on 

Some Economic Insects 



and Plant Diseases of Indiana 



SB 824 
.16 A5 
1907 
Copy 1 



BENJAMIN W. DOUGLASS 

State Entomologist 
INDIANAPOLIS, INDIANA 



1907 



A PRELIMINARY BULLETIN 



ON 



Some Economic Insects and Plant 
Diseases of Indiana 



Benjamin W. Douglass 

State Entomologist 
INDIANAPOLIS, INDIANA 



1907 



INDIANAPOLIS 

\VM. B. BURFORD CONTRACTOR FOR STATE PRINTING AND BINDING 
1907 






o»of a 



Some Economic Insects and Plant Diseases 
of Indiana 



Office of the State Entomologist 
BENJAMIN W. DOUGLASS 



It has been claimed by eminent scientists that all the diseases 
of men common in Indiana, even to the notorious malaria of the 
swamps, were brought into this territory by the people who came 
from the older settlements. A similar statement would hold true 
for most of the insect and fungus parasites that infest the plants 
of the State. It has not been such a long time since it was possi- 
ble to grow fruit of all kinds and have a large percentage of per- 
fect specimens in the harvest. 

Today, however, there have been so many injurious insects in- 
troduced and so many fungus enemies have made their appear- 
ance that the problem of the horticulturist and the agriculturist 
is a great one, and one that will tend to increase instead of de- 
crease as time goes on. Today the fruit grower, even though he 
has but a few trees or berry bushes, must own a spray pump of 
some sort, and he must exercise a great deal of judgment in its 
use. Spraying has been played up for so many things that the 
novice is apt to be misled into thinking that it is a panacea for 
all orchard troubles, when, as a matter of fact, it is worthless 
unless done intelligently and with a proper regard for the re- 
quirements of the particular trouble involved. Before you start 
to spray be sure that you know what you are spraying for, and 
try to learn the best time to apply the proper spray or poison, 
and learn what that poison should be. 

We may divide the things that it is necessary to spray for 
into three general groups, each group requiring special treat- 
ment. 

First Group — Biting or Chewing Insects. 

This class includes all of the more common larval farms which 
damage the plant by actually eating the tissues. They may best 
be handled by an internal poison placed on the leaves or other 
plant parts that they damage. Of such poisons Paris Green is 

(2) 



4 

the most commonly used and is, perhaps, one of the best. Ex- 
amples of this group are the tomato worms, codling moths, elm- 
leaf beetles, etc. 

Second Group — Sucking Insects. 

Insects of this class damage the plants by inserting their mouth 
parts through the epidermis and securing their nourishment di- 
rectly from the interior of the plant. They can not be reached 
by any poison such as would kill the chewing insects, but must 
be treated with a remedy strong enough to kill them by direct 
contact. This fact makes the sucking insect an especially hard 
class to fight, as many of the things used to destroy them are 
apt to damage the plant as well. For this class of insects the 
most common remedies are Coal-oil Emulsion, "Whale-oil or other 
soap, strong tobacco juice, and the Lime-Sulphur-Salt wash. The 
San Jose and other scales and the plant lice are examples of this 
class of insects. 

Third Group — Fungus Enemies. • / 

There are almost innumerable parasitic fungi that infest wild 
and cultivated plants, and often they become a very serious pest 
and do tremendous damage. They consist of small, often micro- 
scopic, plant bodies, which live in the body of the "host" plant, 
as it is called, and gradually cause its death, either by the de- 
struction of the tissues or by the production of a direct poison. 

The universal remedy for all such fungi is a solution of copper 
sulphate, either pure or with the addition of a certain percentage 
of lime, to neutralize the free acid of the sulphate and thus pre- 
vent damage to the leaves of the plant. 

Then there is another group composed of both the plant and 
animal parasites, for which there is but little that can be done. 
Among these are the black knot on the cherry and the plum, 
and the blight in the pear, and the various kinds of borers that 
affect the boles of trees. While we know what the latter are, 
we have not ready means of combating them without destroying 
the trees. There are many problems that will come under this 
latter class, and each requires individual study to develop the 
point at which it may best be attacked. For the most part, how- 
ever, the problems that confront the farmer and tree grower of 
any sort can be found under one of the three first heads given, 
and the whole secret in the successful treatment of plant para- 
sites is to be sure of what you want to do and then do it thor- 
oughly. 



INSECTICIDES; 

For the First Group — Biting Insects. 

The best poison to employ for this class is undoubtedly Paris 
Green, as it is easily prepared and is cheap, and its presence can 
usually be detected owing to its color, thus preventing it being 
taken for any other substance, as it is very poisonous. It is an 
arsenic preparation, and when used in solution must be constant- 
ly stirred to prevent settling, as it is heavy and settles rapidly. 
It is often advisable to add a bit of lime to the Paris Green 
solution to prevent any damage to the foliage which might re- 
sult if it were used pure. On ordinary foliage, however, it is 
not necessary to use this precaution, as it is not probable that 
any harm will result from the use of the poison. It can be safely 
used in the proportion of one pound to one hundred and fifty gal- 
lons of water, and this proportion will prove effective for most 
purposes. 

Other arsenical poisons are not mentioned here owing to the 
lack of space and because none of them are any better than Paris 
Green and a discussion of them might tend only to confuse the 
intending sprayer. 

For the Second Group — Sucking Insects. 

This class of insects is a very hard one to reach by any method 
of spraying, and a great many different preparations have been 
tried from time to time, but with variable results. What has 
proved successful in one locality has, for one reason or another, 
entirely failed when applied by other experimenters at other 
places. The advent of the San Jose scale and the increasing 
numbers of the various species of plant lice have made spray- 
ing with contact poisons a rather recent development in agri- 
cultural practice, and today it is far from being an exact science. 
Any poison for this class of insects must be strong enough to 
kill the insect by contact and still do no damage to the tree, 
and this result is sometimes hard to obtain. We can not devote 
any time to a review of the experiments that have been car- 
ried on in various parts of the country for some time, but simply 
give the formulas of some of the preparations that have in some 
localities been found effective. Probably any of them will prove 



6 

effective and harmless to the tree if properly made and carefully 
applied. In no case should any spraying solution he so lavishly 
applied that the tree drips. It will require practice to develop 
sufficient skill to spray a tree just enough, that is, until it is com- 
pletely coated with the solution and no more. 

LIME-SULPHUR-SALT WASH. 

The following formula is one that is recognized and recom- 
mended by the foremost economic entomologists in the country, 
but it may be varied considerably without apparently detracting 
from its efficiency. 

Lime 50 pounds 

Sulphur 50 " 

Salt 50 " 

Water 150 gallons 

Add enough water to the lime to slake it thoroughly and im- 
mediately add the sulphur. Boil for an hour or so with only 
water enough to keep the mass liquid, until the solution be- 
comes a deep amber color. Have the salt dissolved in water and 
add it to the boiling mass. After it has all been mixed together, 
boil for at least another hour and then add water enough to 
make up the one hundred and fifty gallons, and spray it as soon 
as possible. It is more efficient when used warm, and some of 
the failures with this wash have undoubtedly been due to the 
use of stale solutions and to careless boiling. 

One objection to this wash is that it is decidedly "messy" to 
work with, and the man at the spray pump is certain to ruin his 
clothing and is fortunate if he keeps the spray from his eyes, 
thus causing serious inflammation. It is always advisable with 
this or any other spray to wear very old clothing that will never 
be used for any other purpose, and to protect the hands and 
face in some way. Automobile goggles would serve admirably 
to keep the spray from the eyes. 

The Lime-Sulphur-Salt wash can only be used during the 
dormant period of the year, as it is fatal to foliage. 

For summer use against the San Jose and other scales, and 
against the myriad forms of plant lice that are every year be- 
coming more and more common, there are several ways of using 
coal-oil effectively. 

There are now being made certain kinds of spray pumps that 
automatically spray a mechanical mixture of coal oil and water 



by the use of compressed air. The oil and water are carried in 
separate tanks and are conveyed in separate lines of hose to 
the nozzle, where they are mixed. 

Then there is the old and tried coal-oil emulsion, made by using 
any kind of strong soap to keep the oil from separating from 
the water. The emulsion has the advantage of staying on the 
affected parts of the plant for a longer time than the plain oil. 
Sometimes this is not to be desired, as the long application may 
result in foliage damage. 

Careless spraying is worse than no spraying at all, for it not 
only fails of its object but it is expensive, and it may possibly 
result in actual damage to the tree. This is especially true in 
the case of the sprays used for the control of the scale insects, 
and this department is in no way responsible for any damage 
that may result from the use of any spray, whether recommend- 
ed in these pages or not. The best that we can do is to advise 
the use of sprays that have proved effective in other cases. 
Under changed conditions the results may be altogether different. 
Effective spraying is largely a matter of individual requirement 
and must be intelligently worked out for local conditions. 

SAN JOSE SCALE. 

(Aspidiotus perniciosus Comstock.) 

So much has already been written relative to the danger aris- 
ing from infection with San Jose scale that no argument is nec- 
essary to convince the average citizen of the desirability of com- 
bating this pest with all the vigor that we can command. We 
will briefly review its important characteristics and, while it is 
not difficult to recognize, we will call attention to the fact that 
the genus "Aspidiotus" contains several other species that are 
very similar to the Aspidiotus perniciosus, and any of them may 
hecome very dangerous to plant life. Among these are the Put- 
nam Scale (Aspidiotus ancylus Putnam). This is an insect so 
similar to the San Jose Scale that even the most expert sometimes 
confuse them. It has been claimed that the Putnam Scale does 
not become numerous enough to damage a tree, and lliis state- 
ment has led some entomologists to make the mistake of calling 
San Jose scales by another name simply because they were not 
thick on the tree. In general, it should be remembered, it makes 
but little difference what the scientific name of any insect is if 



it is assured that it is doing damage to vegetation, and any scale 
that shows signs of attaining considerable numbers should be 
treated exactly as you would treat a well-authenticated case of 
San Jose scale. 

Life History. — The San Jose scale began life as a minute 
orange yellow insect, crawling freely about over the trunks and 
limbs of trees, whereupon its parent is attached. It is in this 
stage that the pest is most generally distributed by birds. It 
will crawl upon the feet and legs of the bird and be carried, pos- 
sibly, great distances before again happening to crawl off on an- 
other tree. • 

This period of activity continues for, at most, a day or two, 
when the young scale settles down and begins to secrete the plate 
or scale proper which cements it firmly to the bark. It grows 
during the summer, feeding on the plant juices, which it draws 
through the bark with its probocis, and in early fall the eggs are 
fertilized in the body of the female by the winged male. 

At the approach of winter the insect (still containing the half- 
grown young) ceases feeding and becomes dormant, to resume 
feeding at the first sign of warm weather. Early in June the 
young attain their full size and emerge from the body of the 
parent, thus completing the life cycle. The production of young 
is continued throughout the season, two broods appearing, one 
in August and one early in October. 

Adult Scale. — The adult scale appears as a small, rounded 
plate, grey in color, the center darker and elevated, the whole 
insect not more than one-sixteenth of an inch in diameter. On 
a badly-infested tree the scales will be so close together as to 
completely hide the bark, giving the branch an unhealthy, scurfy 
look. 

SCUEFY SCALE. 

(Chionaspis furfurus'Fitch.) 

While common and widely distributed, this scale has seldom be- 
come numerous enough to cause any material damage. 

As will be seen by the illustration, the male and female dif- 
fer considerably in form and size. At one stage in its life his- 
tory the male is winged, as are the males of the majority of the 
scale insects. 



«) 

Under favorable conditions this scale may become destructive, 
and wherever they seem to be multiplying it would be advisable 
to use on them the same measures recommended for the San 
Jose Scale. 

COTTONY MAPLE SCALE. 

(Pulvinaria innumerabilis Rathvon.) 

During, the past two years the cottony maple scale has killed 
many trees in Indiana. It has not been confined to maples en- 
tirely, for trees of several other genera have been attacked and 
killed. Little or no attention has been paid to it in spite of its 
deadly character. 

Life History. — After hibernating on the twigs of trees all win- 
ter, the female lays large quantities of eggs in May and June. 
It is at this season that the scale is most conspicuous, clinging 
to the under side of the twig and surrounded at one end with 
great masses of cottony padding, which is developed from the 
body simultaneously with the eggs. This cottony substance is 
persistent on the branches through the summer and until worn 
off with wind and rain. 

The eggs hatch in a short time and the young at once migrate 
to the leaves, where they attach themselves in rows along the 
veins and begin feeding. They grow rapidly, and as summer ad- 
vances the males and females are differentiated, the males de- 
veloping wings. At the approach of fall the fertilized females 
attach themselves to the under sides of the twigs, where they 
remain all winter. The male dies at the end of the summer. 

Treatment. — Winter spraying with Lime-Sulphur-Salt wash or 
with whale-oil soap is the best means of controlling the cottony 
scale. 

On affected trees the leaves fall persistently throughout the 
season, often ending with the death of the tree. These leaves 
should be carefully raked up and burned, as they are an active 
source of infection for other trees. 

Summer spraying would have to be very thorough to be ef- 
fective, as every leaf on a badly affected tree is a host of in- 
numerable scales. Sometimes a tree that has been completely 
stripped of its leaves and seemingly killed will put forth a new 
set of foliage in the fall, but it is not likely that such a tree could 
withstand the succeeding winter. 



10 



PLANT LICE. (Aphids.) 

There are many kinds of plant lice that affect cultivated plants. 
Almost all of them are dangerous and require prompt treatment. 
Many lice, such as the cherry and apple aphids, winter in the 
egg state, and the eggs are laid on the young twigs of the trees. 
In this way they may be distributed in nursery stock. The 
woolly apple louse forms a characteristic grayish cottony mass 
about it. It feeds on the apple and is one of the worst pests we 
have to deal with. Owing to the fact that one stage of the in- 
sect infests the roots of the trees, it is very difficult to treat, and 
a tree that is badly infested should be destroyed and the ground 
thoroughly dug up and exposed to the air. It will be safe to 
replant the same spot with another tree, but not with an apple. 
I have had partial success in treating this louse with carbon bisul- 
phid, using an ounce of the liquid in each of several holes punched 
in the ground around the tree at a distance of about two feet 
from the trunk. 

During the season of 1907 the common oat louse became so 
plentiful that many fields of oats were ruined. The only practi- 
cal treatment so far suggested is to burn over the fields and thus 
reduce the number of individuals to affect next year's crop. The 
same field should not be planted in oats again without a rotation 
crop of clover or corn. The number of lice was due probably 
to the peculiar weather conditions of the preceeding spring. Ac- 
companying the presence of the oat louse was a characteristic 
red rust that sometimes affects the grain regardless of the pres- 
ence of any insect. Lice on the rose bushes sometimes become so 
numerous as to kill the tender growing tips or to destroy the 
foliage. In green houses it is a common practice to use tobacco 
smoke — in the open a strong, solution of tobacco made by boil- 
ing cheap clippings and stems will prove very effective if sprayed 
on the affected parts. For any of the lice this tobacco solution 
is a standard remedy. Where there is a large area to be treated 
the coal-oil emulsion will be found to be cheaper and perhaps 
more effective. 



11 




SAN JOSE SCALE. SLIGHTLY ENLARGED. 



m 



12 




OYSTER SHELL SCALE. ENLARGED. WHERE IT BECOMES AS COMMON 
AS SHOWN IN THIS SPECIMEN THIS INSECT IS QUITE 
AS INJURIOUS AS THE SAN JOSE SCALE. 



13 



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SCURFY SCALE. (MALE) SLIGHTLY ENLARGED. 



14 




LARVA OF THE CECROPIA MOTH, A TYPICAL CHEWING JNSECT. NATURAL SIZE. 



15 




THE WORK OF THE TUSSOCK MOTH. 



16 




PALL WEB WORM AND ITS WORK. 



17 




WORK OF THE CATALPA SPHINX MOTH. WHERE IT HAS MADE 

ITS APPEARANCE THIS INSECT HAS RENDERED 

CATALPA GROWING IMPOSSIBLE. 



18 




WORK OF THE LOCUST BORER. IN THIS PLANTATION TWENTY-SIX 

PER CENT. OF THE TREES HAVE BEEN EATEN OFF, AND 

ALL OF THE OTHERS ARE AFFECTED. 



19 



CODLING MOTH. 

. It is the presence of this insect that makes apple growing dif- 
ficult in this country. It is practically impossible to grow apples 
in Indiana without spraying and secure anything like perfect 
fruit. The insect hatches from the cocoons in the late spring 
and at once lays its eggs on the young apples, mostly at the 
flower end. The trees should be sprayed just after the blossoms 
fall so as to fill the calyx with the poison, as many of the young 
larva enter the fruit at this point. In case of very wet weather 
it is advisable to give a second spraying about two weeks later 
and again early in July. The late spraying is to meet a second 
brood of the insects that appear about that time. The first spray- 
ing may be of Paris Green or other arsenic poison, the subse- 
quent ones with poisoned Bordeaux. Appendix A. 



CURCULIO. 

This is a small beetle that affects cherries, apples and plums 
— notably the last. The adult lays the eggs in a characteristic 
crescent-shaped slit in the young fruit, and hence they can not 
be reached by any poison, as they are completely covered by the 
fruit when they hatch. The adult beetles have a habit of feeding 
on the fruit, however, and some of them may be poisoned with a 
Paris Green spray applied just after the blossoms fall. It is also 
possible to gather the small beetles by jarring them down from 
the tree and catching them on sheets spread on the ground. Es- 
pecially constructed "Curculio Catchers" are sometimes em- 
ployed for this purpose and are made so that they may be moved 
from tree to tree. The insects are collected from the sheet and 
destroyed. 

LEAF EATERS. 

There is such a host of leaf eating insects that our space will 
not permit a description of each species that can be found doing 
damage to Indiana crops. We will only mention some of the 
most common and destructive. Since the treatment for all of 
these insects is the same, it will not be difficult to handle any 
new problem that may present itself along this line. 



20 



TOMATO WORM (Sphinx Moth). 

This sometimes troublesome insect is the larval form of one of 
the Sphinx moths. The caterpillar is distinguished by the pres- 
ence of a peculiar horn on the tail, which is commonly supposed 
to be venomous. As a matter of fact, it is absolutely without 
poison of any kind, and the worm can be handled with impunity 
by anyone. The insect passes the winter in the resting or pupal 
stage in the ground, and many of them will be destroyed by 
thorough cultivation. In small gardens where the worms are 
doing any considerable damage they may best be removed by 
hand picking. Large fields that are badly affected should be 
sprayed with Paris Green early in the season before the fruit 
attains any size. This will probably remove most of the brood 
and make the matter of hand picking the few that remain a com- 
paratively easy task. Often this insect is attacked by a parasitic 
fly that lays its eggs on the body of the worm and eventually 
causes its death. The small cocoons of the fly are sometimes to 
be found sticking all over the bodies of the caterpillars. Such 
specimens should be allowed to develop, as they are doomed to an 
early death, and by allowing the flies to reach maturity an addi- 
tional control is placed over the remaining pests. Other forms 
of the Sphinx Moth affect different plants. One of them is very 
destructive to tobacco, and should be handled just as the tomato 
worm is handled. 

CATALPA SPHINX. 

Quite recently the so-called Catalpa Sphinx has been intro- 
duced into Indiana and is causing great damage to the Catalpa 
Trees. It seems to be a very thrifty form and is one of the most 
difficult to control, owing to the character of the plants it feeds 
on. Neither spraying nor hand picking is practical, and the 
only method of control seems to be thorough cultivation under 
the trees in both late fall and early spring. Unless the insect 
can be exterminated in this way it will mean that Catalpa grow- 
ing in forest plantations will soon be in the same condition as 
Black Locust growing, as the latter tree is thoroughly impractical 
because of the damage caused by the uncontrollable locust borer. 



21 



SLUGS. 

These slimy larvae sometimes become very injurious on cherry 
and other trees. They can be destroyed with Paris Green or may 
be treated with common lime dusted on dry. Their sticky bodies 
hold the lime and they are quickly killed. 

POTATO BUGS. 

This insect is so common and so widely distributed that it does'' 
not require any description. They may be gathered by hand 
and destroyed where they are not too thick. This; is especially 
effective in the early part of the season, and will prevent serious 
devastation later in the summer. The standard spray, of course, 
is Paris Green. 

ELM LEAF BEETLE. 
ELM LEAF CATERPILLAR. 

Both of these troublesome insects are liable to be met with 
in almost any part of Indiana, and should be promptly treated. 
The damage is done by the larva of both insects and by the adult 
beetles as well. Paris Green sprayed on the trees when the pests 
make their first appearance is the only remedy worth consid- 
ering. 

THE TUSSOCK MOTH. 

This troublesome insect is usually periodical in its attacks 
on trees, and is making its appearance in dangerous numbers for 
the first time in some years. 

The moth winters in the egg state, and early in the summer the 
young larvae hatch and at once crawl to the foliage and begin 
to feed. The eggs are laid by the female moth on the old cocoons, 
and as these cocoons are frequently situated on houses and other 
objects away from the trees the young can be kept from the foli- 
age by banding the trees with some sticky preparation which will 
keep them from crawling up the trunk. In the winter the cocoons 
bearing egg masses should be collected and burned so as to de- 
stroy all the young that are present. A favorite place for the 
situation of cocoons is under the overlapping weatherboards on 
the sides of houses. In summer, after the caterpillars make their 
appearance, they can be destroyed by spraying the trees with 



00 



Paris Green solution. This remedy is proving very successful in 
Indianapolis, but it must be thoroughly applied, and if washed 
off by the rain it should be repeated. The larva or caterpillar 
of this moth is one of the most beautiful of all the curious array 
of insects. It may be easily recognized by the presence of sev- 
eral tufts of white hair on the back, from which it takes its 
name of the Tussock Moth. At the head are two long pencils 
of brownish hair, with a single similar one on the tail. The 
front part of the head is bright red in color and a couple of red 
glands occupy segments near the tail. The hairs of this cater- 
pillar are barbed, and sometimes cause more or less irritation to 
persons of tender skin when they are carelessly handled. 

Suggestions 'given for the few forms enumerated above will 
suffice to give a key to the treatment required for almost any leaf- 
eating insects. Any special forms that may at any time cause 
damage should at once be sent to the office of the Entomologist 
for identification, and suggestions relative to their treatment 
will be sent promptly. 

BORING INSECTS. 

There are such a host of insects that damage the trees by bor- 
ing in their trunks or limbs that it is impossible to more than 
mention them in the short space that we have available in this re- 
port. One of the most destructive and important from an eco- 
nomic standpoint is the Locust Borer, an insect so common and 
so widely distributed that locust growing for fence posts is im- 
practical over the greater part of eastern America. In Indiana 
I have yet to find a locality where the Locust Borer is not firmly 
established, and is already doing very great damage to the plan- 
tations that have been set out. There is no practical way of con- 
trolling this insect, and the only thing to do is to plant other 
trees that are not bothered in this way. Other borers affect the 
apple, peach and plum among our orchards, and to a certain 
extent they may be exterminated by cutting out and burning 
the affected trees. Where the cutting and burning is done thor- 
oughly there is no reason why this treatment should not be suc- 
cessful. I know of an old peach orchard that was badly affected 
with the trunk borer when a friend of mine took possession of it. 
After three years' work he has succeeded in exterminating the 
borers, and most of the trees are completely recovered from their 



23 

injuries and are in very fine shape today. Apple borers may 
sometimes be very successfully cut out without hurting the tree 
greatly. It would also be worth while to experiment with car- 
bon bisulphid — pouring some of it into the channels made by the 
insects and covering the mouths of the burrows with putty to 
keep in the fumes. In Prance some successful experiments have- 
been carried on by using a mixture of formaldehyde and gly- 
cerine in the same way as suggested for the carbon bisulphide. 
In some parts of Indiana, the Elm-tree Borer has done con- 
siderable damage, and wherever it makes its appearance it should 
be promptly attended to, as it rapidly spreads from one tree 
to another and in a short time a large area is worked over and 
destroyed. 

-Numerous root borers affect different kinds of trees, and some 
of them may be gotten rid of by the liberal use of tobacco dust 
or wood ashes around the roots of the trees. Any of the potash 
salts are also valuable in this same connection, and even if they 
do not kill the borers they will so stimulate the tree that it may 
be able to outgrow the effects of the borer damage. 

FUNGKJS DISEASES. 

In the control of fungus and bacterial diseases it must always 
be borne in mind that the trouble is usually transmitted in the 
form of very minute spores and any treatment must be thorough 
enough to kill all possible chances of any spores living through it, 
Often the body of the fungus plant itself is miscroscopic in size 
and the spores (which are to the fungus plant exactly as seeds 
are to the flowering plants) are infinitely small. In regard to 
many forms of fungal disease our knowledge is still very incom- 
plete, but gradually we are finding new remedies for pests here- 
tofore considered uncontrollable, and in the future we may ex- 
pect great advances along the line of plant pathology. There 
are still some forms that do not yield to any treatment. In fact, 
it is not definitely known just what is the cause of certain plant 
diseases, and for lack of any remedy we can simply use preventa- 
tive measures and cut out and burn all affected plants. Peach- 
yellow, Black-knot on the plum, Pear-blight, some of the root 
galls, and a number of other troubles come in this class on which 
scientists are still working. 



24 



APPLE (Anthracnose). 

This disease is caused by one of the fungi in the genus Gloeo- 
sporium, and causes small dark sunken spots in the fruit. It 
should be sprayed with Bordeaux both before and after blos- 
soming. 

SOOTY FUNGUS. 

This fungus causes the fruit to appear speckled, as with a thin 
coat of soot or fly specks, and is caused by "Leptothyrium pomi," 
a minute fungus. The quality of the fruit is not injured but it 
is rendered less marketable. The spraying for Anthracnose will 
probably be all that is needed to prevent this disease. 

BLIGHT. 

The same bacteria that causes the blighting of pear is some- 
times responsible for damage to the apple. Affected parts should 
be cut out and burned. 

APPLE SCAB. 

This is a disease that appears at its worst in cool, damp sea- 
sons, and at such times it is difficult to control. The fruit and 
foliage are both affected and as a result the standing crop is lost 
and the crop of the succeeding year prevented by a lack of leaf 
work. Early spraying with Bordeaux, as recommended above, 
should be effective for this trouble. 

BLACKBERRY (Orange Rust). 

This common disease of the Blackberry is best controlled by 
burning all the affected parts. It is transmitted by the red spores 
on the leaves in summer, and any treatment should be very 
thorough, or it will be time wasted. 

CHERRY (Black Knot. See Plum). 
SHOT-HOLE FUNGUS. 

This fungus affects the leaves of the cherry and causes them 
to become spotted. The spots later turn dark and fall out, giv- 
ing the appearance of having been shot with a shot-gun. Dilute 
Bordeaux, early in the season, will prove effective. 



25 



CHERRY ROT. 

This is not a common disease in most parts of Indiana, but 
it may become very destructive. The fruit is affected and dries 
up, often remaining on the tree until the next season. These 
dried fruits are responsible for the fungus living over the winter, 
and*' as a means of prevention all affected fruit should be care- 
fully gathered and destroyed. Bordeaux should be used before 
the blossoms are out. 

CUCUMBER (Anthracnose). 

Causes circular spots in the leaves to die. Also affects the 
stem. Bordeaux will be found effective if the trouble becomes 
serious. 

WILT. 

This is a disease of cucumbers, melons and squashes that is 
caused by the presence of a bacteria growing in the tissues of 
the plant. The water supply is eventually cut off and the vines 
die for lack of moisture. It is a very difficult thing to control 
and the only practical treatment is the extermination of the 
trouble by gathering and burning all affected vines. 

GRAPE. 

There is a long list of fungi that affects the grape, and for the 
most part our knowledge relative to their identification is not 
very definite. Most of them can be prevented by a thorough 
spraying with Bordeaux early in the spring before the buds open 
and again after the fruit has set. 

MUSKMELON (See Cucumber). 
OATS. 

Rust on the oats is rather common during the wet seasons. 
It is also usually associated with the presence of the green oat 
louse. As a rule it does not do any great damage. There is no 
practical remedy. 

SMUT. 

The smut of oats sometimes causes very serious losses and can 
be prevented by using the formalin treatment of the seed. Ap- 
pendix (B). 



26 



PEACH. 

The crown gall of the peach and pear usually occurs at the 
root collar and takes on the form of a large excressence just 
below the surface of the ground. As yet we have had but few 
reports of it from Indiana, but conditions in other States indi- 
cate that it should be watched for and promptly gotten rid of. 
The only treatment is cutting out and burning. 

LEAF CURL. 

During cool, moist springs this trouble on the peach may be- 
come very serious. It can be prevented by early spraying with 
Bordeaux before the buds open. 

PEACH YELLOWS. 

This is a serious disease of unknown cause that must be treat- 
ed by the removal and burning of all affected stock. It is char- 
acterized by the early ripening of the fruit, which is usually 
"off color" for the variety, excessive branching of the new 
shoots, and the production of bunches of slender, wiry twigs. 
The color of the foliage is also usually of a pale, sickly yellow 
color. It is one of the most dangerous diseases affecting the 
peach. 

PEAR BLIGHT. 

In this disease the branches wilt and the foliage turns dark 
but does not fall from the tree. It is caused by a specific bac- 
teria and is contagious from one tree to another. It can be 
checked and eradicated by thoroughly cutting out and burning 
all affected parts. 

PLUM (Black Knot). 

This disease is caused by a fungus that infests the branches 
and causes unsightly excressences to form along them. It is con- 
tagious and destructive but can be controlled by cutting -out the 
knots in the winter and burning them. 

SHOT-HOLE FUNGUS (See Cherry). 

RASPBERRY (Anthracnose). 

This fungus is sometimes so severe in its attacks on the rasp- 
berry that it renders its successful cultivation practically impos- 
sible. It occurs on the young canes as round, purplish spots, and 



27 

winters in the spore condition on the dead wood. Thorough cut- 
ting out of all affected stock and spraying the remainder well 
with Bordeaux would probably be. effective in checking damage 
done by this pest. It is almost impossible to propagate young 
plants from stock that is affected with anthracnose, and nurseries 
affected with it will not be issued certificates. 

WHEAT RUST. 

This fungus (Puccinia Gramiriis) is difficult to control. In re- 
gions where it is very common wheat growers are trying to se- 
lect varieties of wheat that are rust proof. There are no sug- 
gestions as to its control. 

STINKING SMUT. 

This fungus trouble is sometimes very destructive to wheat, 
and can be prevented by the formalin treatment as suggested 
for oat seed. Appendix (B). 



APPENDIX A. 



BORDEAUX MIXTURE. 

Copper Sulphate : . . . . 6 pounds 

Lime 4 pounds 

Water 50 gallons 

Dissolve the copper sulphate and the lime in separate vessels, 
using a couple of gallons of hot water for each. When dissolved 
add the lime slowly to the copper solution and then put in enough 
water to make up the full fifty gallons. 

Bordeaux Mixture is not an insecticide at all but is used as a 
preventative against fungus parasites. The copper acts by de- 
stroying the spores of the fungus, and the lime helps to make it 
stick on the tree. It is often valuable to add Paris Green to the 
Bordeaux and thus secure effective work against insects as well 
as against fungus. For this purpose the Bordeaux solution 
should be considered simply as so much water, and the proper 
quantity of Paris Green added as directed elsewhere in this bul- 
letin. The excess of lime in the Bordeaux will be sufficient to 
neutralize the Paris Green. 



MAR 2 1908 2g 

APPENDIX B. 

FORMALIN TREATMENT. 

Formaldehyde is obtainable in what is known as a 40 per cent, 
solution. One pound of this solution should be diluted with 50 
gallons of water and the grain well sprinkled with it. The seed 
should then be immediately covered with a wet sheet and allowed 
to remain for several hours. Allow to dry before planting. 

For potato scab this same solution can be used but should be 
diluted only half as much. Soak the potatoes for three hours be- 
fore planting. 

APPENDIX C. 
COAL OIL EMULSION. 

The following formula for Kerosene Emulsion is from Prof. 
J. B. Smith's Economic Entomology: 

Hard soap, shaved fine V2 pound 

"Water 1 gallon 

Kerosene 2 gallons 

Dissolve the soap in boiling water; warm the kerosene and 
add the boiling hot suds to it ; then churn with a force-pump for 
a few minutes and we get first a milky appearance, which yields 
rapidly to a cream, and this to a soft butter-like mass. When 
cold it will adhere to glass without oiliness, and the emulsion 
thus made, containing sixty-six per cent, of kerosene, will re- 
main unchanged for some time, and may be mixed with water 
to any extent. Soft water must be used for best results, and 
with very hard water a real emulsion can not be obtained at 
•all without the addition of borax sufficient to soften it. Diluted 
from nine to twelve times, this emulsion is very effective against 
plant lice, many scale insects and such others as yield to contact 
insecticides in general. Plants vary in their resistance to this 
material, not only absolutely, but relatively under different cli- 
matic conditions. Diluted nine times, few insects resist its effects 
and only the hardier plants can be safely treated ; diluted fifteen 
times, only the green plant lice are affected, while some foliage 
shows material injury. Where plants do not readily stand a 
dilution of twelve times it is better not to use the emulsion at 
all. For winter use the emulsion is useless as against dormant 
scales, and more injurious to trees than the undiluted oil. 



■xdkhky OF CONGRESS 



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